A Study of the Relationship Between Sudden Infant Death Syndrome and Environmental Factors1

The incidence of the sudden infant death syndrome (SIDS), a major cause of death in children one week to one year of age, has been shown to be increased during the winter season and among low socioeconomic class and low birth-weight infants. In one study, the incidence of SIDS was shown also to be correlated with rapid temperature fall and increased wind speed during the winter time. Since these epidemiologic features of the disease and the relationship to meteorologic changes might be explained by increased air pollution levels occurring in lower economic areas during the winter heating season, a study was undertaken to examine the relationship between SIDS and the air pollutant, sulfur dioxide (SO2). Also, the relationships between SIDS and certain meteorologic variables (temperature, wind speed, precipitation, and humidity) were examined using a stepwise, multivarient regression model. A total of 942 deaths from SIDS were studied over a four-year period in Chicago. The only consistent finding was an inverse relationship between SIDS and temperature in three of the four years of the study. No consistent relationship was found with the other meteorologic variables. Further, no significant differences in SO2 concentrations were found in comparing days when a SIDS death occurred and control days in the same community during the same season of the year. These data do not suggest that atmospheric SO2 levels play an important part in SIDS but the effects of other environmental pollutants should be studied.